This invention relates to mounts for probes and to probe assemblies including such mounts.
The invention is more particularly concerned with stress-relieving 5 mounts such as for fluid-gauging probes.
The level of fuel and other dielectric fluids, such as lubricants, in aircraft may be measured by means of a capacitance probe comprising an outer tubular electrode and an inner coaxial rod electrode. The probe is mounted to extend vertically in a tank or reservoir such that fluid fills the outer electrode to the same height as fluid in the tank. As the fluid level in the tank or reservoir changes, therefore, a corresponding change in the level of fluid in the outer electrode is produced which causes a change in the value of capacitance between the two electrodes. By measuring the capacitance, the fluid level can be determined.
The length of the probe used is dictated by the size and shape of the tank or reservoir and can by up to about 800 mm long. The probe is usually secured at its upper end to an opening in a wall of the tank through which electrical connection of the probe is made. With probes of short length, it may be sufficient to mount them at the upper end only. With longer probes, however, it has formerly been necessary also to support them close to their lower end since the vibration and accleration to which they can be subjected leads to stress in the mount and the probe itself which can lead to breakage or damage to the probe. In many tanks or reservoirs, however, it is difficult to provide a mount at the lower end of the probe. This is especially the case where the tank or reservoir is of a flexible elastomeric construction. The provision of a mount at the lower end of the probe, furthermore, can require a hole to be cut through the floor of the tank or reservoirs consequently giving a site of weakness and possible leakage, and adding to the cost of installing the fuel probe.